Determining Thermal Parameters Of A Building

ABSTRACT

Embodiments of the present disclosure include techniques for determining thermodynamic properties of buildings. In one embodiment, a method for determining a building UA-value comprises monitoring indoor and outdoor air temperature during a drift phase over a first time period, and monitoring a temperature control system run time during a second time period over which the temperature control system in the building restores indoor air conditions to an initial state at the beginning of the first time period. Additionally, an amount of heat energy change may be determined during the second time period. Embodiments may determine thermal resistance of the building from data obtained during over the two time periods, for example.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Patent Application No. 62/684,512, filed Jun. 13, 2018, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to thermal management, and in particular, to determining thermal parameters of a building.

A basic understanding of the thermal performance of every building is necessary where heating and cooling is being delivered to the space. The thermal performance of a building is traditionally defined by its total amount of exposed surface area and overall resistance to heat transfer, or UA-value (or just U-value), as well as the corresponding maximum rates of heat loss or heat gain, referred to as the peak heating and cooling loads.

Building UA-value must be known in order to determine peak loads, which are then used to size the mechanical heating, ventilation, and air-conditioning (HVAC) equipment. Accurate determination of the building loads is a critical requirement for installing a cost-effective, and properly functioning HVAC system, and has a direct impact on occupant comfort levels, indoor air quality, building efficiency and energy use, and overall system durability.

Undersized HVAC equipment will not be capable of maintaining desired indoor temperatures or humidity levels. Oversized HVAC equipment will operate with reduced efficiency levels, lower service life expectancies, and struggle to maintain indoor comfort levels, especially with regard to humidity control during the summer months.

The UA-value for a building is typically quantified by creating a theoretical heat transfer model to determine its overall resistance to heat transfer. The methods used to perform the calculations are time consuming and error prone. The area, orientation, and thermal resistance of every building surface needs to be defined. Parameters that describe the quality of the distribution system comprised of ductwork, hydronic piping or fan coils must also be defined. To do so accurately requires rigorous inspection of the building and a detailed accounting of each component, its construction quality, and thermal resistance value.

This process is especially difficult for older buildings where floor plan drawings and construction details are not available. In many cases, theoretical representations of a building used to perform these calculations do not reflect reality.

DRAWINGS

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 illustrates sensors for determining a thermodynamic property of a building according to an embodiment.

FIG. 2 illustrates a method of determining a thermodynamic behavior of a building according to an embodiment.

FIG. 3 illustrates cloud (or Internet) based software and hardware system for determining thermodynamic properties of one or more buildings according to an embodiment.

FIG. 4 illustrates a drift phase of operation according to an embodiment.

FIG. 5 illustrates a recovery phase according to an embodiment.

FIG. 6 illustrates a system according to an embodiment.

FIG. 7 illustrates an example of special purpose computer systems according to one embodiment.

DISCLOSURE

In the following description, for purposes of explanation, numerous examples and specific details are set forth in order to provide a thorough understanding of the present disclosure. Such examples and details are not to be construed as unduly limiting the elements of the claims or the claimed subject matter as a whole. It will be evident to one skilled in the art, based on the language of the different claims, that the claimed subject matter may include some or all of the features in these examples, alone or in combination, and may further include modifications and equivalents of the features and techniques described herein.

Features and advantages of the present disclosure include techniques for determining thermodynamic properties of buildings. FIG. 1 illustrates a building 100 having an internal temperature Tint and external temperature Text. Building 100 may have a temperature control system 101, such as an HVAC, for heating, cooling, or otherwise conditioning the environment inside building. Embodiments of the present disclosure may be used to determine thermodynamic properties including thermal resistance (or equivalently transmittance), and may be used to determine loading, such as peak heating loading or peak cooling loading, for example.

Building 100 may include one or more temperature sensors 102. Sensors 102 may be thermostats, for example. In various embodiments, temperature sensors 102 measure air temperature or humidity, or both, for example. In one embodiment described in more detail below, the thermostats are Internet connected to communicate information to a cloud computer system, for example. In one embodiment, a thermostat may be coupled to the temperature control system 101 for increasing or decreasing the temperature of the building, for example.

FIG. 2 illustrates a method of determining a thermodynamic behavior of a building according to one embodiment. Features and advantages of the present disclosure may include sensing temperature changes in a building to determine a building's thermodynamic characteristics. For example, according to one embodiment, a building is allowed to drift from an initial internal temperature to a final internal temperature based on an external temperature (e.g., external heat or cold). The internal and external temperatures are measured or otherwise monitored over this “drift phase.” Then, during a “recovery phase,” the temperature control system may be turned on and the system determines how long it takes to bring the internal temperature back to the initial internal temperature. Using this process, thermodynamic properties of the building may be determined, such as, for example, thermal resistance, thermal transmittance, UA-value, and peak heat load or peak cooling load, for example

Referring to FIG. 2, at 201, a constant internal/external temperature equilibrium is established. For example, a building may be brought to an initial temperature by temperature control system 101 for a certain amount of time (e.g., 30 minutes for some buildings). At the beginning of a first time period, t1, the temperature control system 101 is turned off at 202. During the first time period, t1, one or more sensors located inside the building measure a plurality of internal temperature values at 203. In one example embodiment described below, sensors 102 of FIG. 1 measure an initial temperature value at the beginning of the drift phase and a final temperature value at the end of the drift phase, for example. Also during the first time period, t1, one or more sensors located outside of, but proximate to, said building, measure a plurality of external temperature values at 204. During the first time period, internal temperature values correspond to a change in temperature inside the building from a first temperature to a second temperature (e.g., from low to high if the external temperature is hotter, or from high to low if the external temperature is colder).

Step 205 begins the second “recovery” phase. At 205, temperature control system 101 is activated to change the temperature inside the building from the second temperature back toward the initial temperature, for example. At 206, the temperature inside the building changes toward the temperature at the beginning of time period t1. At 207, a duration of a second time period over which the temperature inside the building changes to meet the first temperature is determined. For example, the system may determine that it takes 1.5 hours for the temperature control system 101 to bring the building back to the initial temperature at the beginning of the first time period. Finally, a thermodynamic property of the building is determined at 208 based on at least said measuring steps and said determining the duration of the second time period step.

FIG. 3 illustrates cloud (or Internet) based software and hardware system for determining thermodynamic properties of one or more buildings according to an embodiment. In this example, a building 300 may include a thermostat 301 coupled to a computer 303 (e.g., an Internet gateway computer or an internet access point). Thermostat 301 may provide data about air temperature and/or humidity in the building (e.g., Tint), for example. The thermostat 301 may be electrically coupled to an HVAC system 302 for controlling the HVAC system 302, for example. In other embodiments, the thermostat 301 and HVAC system 302 may be directly connected to the Internet 399 (e.g., via a wireless connection, WiFi). Similarly, a weather station 310 may include sensors 311 coupled to Internet 399 via a computer system 312 (e.g., an Internet gateway computer or an Internet access point). Weather station 310 may provide data about air temperature (e.g., external air temperature, Text) and humidity in a particular region nearby or proximate to building 300, for example. In this example, data from thermostat sensors 301 and weather station sensors 311 may be coupled over Internet 399, through one or more network interface units 320, to thermal analysis engine software 322 executing on servers 321 in a cloud data center 310, for example. The data may be stored in data stores 323, such as one or more databases, for example.

In one embodiment, a user may access thermal analysis engine 322 and execute thermodynamic testing on one or more buildings remotely, for example The user may schedule a test to establish an equilibrium between the inside air conditions and the outside air conditions. At the beginning of a drift phase, the HVAC 302 may be turned off (e.g., remotely) and the inside temperature allowed to drift. The initial temperature inside the building, Tint, the initial external temperature Text, and the drift start time may be received and recorded by thermal analysis engine 322, for example. Drift of the inside temperature may be based off heat transfer between the inside and outside of the building. In some cases, the internal temperature may be higher than the external temperature, and the drift will be a decrease in internal temperature. In other cases, the internal temperature may be lower than the external temperature, and the drift will be an increase in internal temperature. At the end of the drift phase, the final temperature inside the building, Tint, the final external temperature Text, and the drift end time may be received and recorded by thermal analysis engine 322, for example.

After drift phase ends, the recovery phase begins and the HVAC 302 is turned on (e.g., remotely). The HVAC 302 may be configured by thermal analysis engine 322 to change the internal temperature of building 300 back toward the temperature at the beginning of the drift phase. The HVAC 302 may be configured to a known energy usage (or capacity), such as a particular number of BTUs/hr, for example. The known energy usage may be recorded by thermal analysis engine 322 as well as the start time of the recovery phase. Thermostat 301 may track the change of the building's internal temperature Tint, for example, and send a trigger to thermal analysis engine 322 when the Tint meets (e.g., is approximately the same as) the initial internal temperature when the drift phase started. The recovery phase may then be over, for example. The time for recovery may be recorded in thermal analysis engine 322, for example.

Thermodynamic properties of the building may be determined based on the drift and recovery phase data. For example, in one embodiment, determining a thermodynamic property of the building is based on starting and ending internal temperature values during the drift phase, starting and ending external temperature values during the drift phase, a duration of the drift phase, an energy usage (or capacity) of the temperature control system 302, and a duration of the second time period. Example calculations are illustrated below.

EXAMPLE

A present disclosure comprises a new method to quickly and accurately determine the thermal resistance (or equivalently, thermal transmittance) and associated peak heating and cooling loads of a building, for example, in order to adequately size the mechanical equipment used for space conditioning, or to quantify the potential impact of energy efficiency improvements to the building envelope, mechanical system, or thermal energy distribution system. More specifically, the disclosure may use a thermostat along with use of the existing heating and cooling system to determine combined building thermal resistance and associated peak heating and cooling load values.

In one embodiment, the present disclosure introduces a method that uses measured data to empirically derive the combined UA-value of a building and its distribution system in place of theoretical models. UA-values (sometimes referred to as heat transfer coefficients or thermal transmittances or simply U-values) are sometimes used to measure how effective elements of a building's fabric are as insulators. That is, how effective they are at preventing heat from transmitting between the inside and the outside of a building, for example. By using measured data that is collected with a thermostat, guesswork and error is removed from the process.

For example, in one embodiment the present disclosure includes a method comprising using the thermostat and data obtained from the nearest weather station to 1) record the starting indoor and outdoor air temperatures and humidity levels; 2) monitor the drift of the indoor and outdoor air temperature and humidity levels over a prescribed period of time with the HVAC system turned off; 3) monitor the amount of time it takes the existing HVAC system to restore indoor air conditions to the initial state. As illustrated below, internal and external temperatures may be used to determine input energy in the recovery phase for a heating system. However, in the case of cooling, humidity may further be used to perform the calculation as a portion of the input energy in the recovery phase is allocated to the latent load, or removing moisture from the air, for example.

By knowing the output capacity of the heating, ventilation, and/or air conditioning (“HVAC”) system, and monitoring the amount of time it takes to restore the indoor air temperature to its original state, the amount of heat gain or loss during the time period with the HVAC system off can be quantified. Since the existing HVAC system is used as part of the test procedure, distribution losses will also be accounted for. The average rate of heat gain or loss and the indoor to outdoor temperature difference are then used to calculate combined UA-value of the building. Once the UA value of the building is determined, the peak heating or cooling loads may be determined using one of a plurality of documented methods.

Features and advantages of the present disclosure allow the temperature of the conditioned space to drift by turning off the HVAC system and monitoring indoor/outdoor temperature and humidity levels, then use a quantifiable source of heating or cooling to monitor the amount of time needed to restore the space to original conditions. As such, the present disclosure is comprised of two primary test phases: (1) the drift phase and (2) the recovery phase.

In one embodiment, the present disclosure provides a method that may use a thermostat capable of recording indoor air temperatures and humidity levels. Ideally, the thermostat would be able to record indoor air conditions as well as HVAC system run-time. In one embodiment, the thermostat may also be used to control the HVAC system through the various stages of the testing procedure. As such, an internet-connected thermostat, for example, may be used for the test. The method may acquire knowledge of outside air temperature and humidity levels from the nearest weather station, for example, during the test. There are several sources for local weather information, such as the free API available through OpenWeatherMap.org.

FIG. 4 depicts representative indoor and outdoor air temperature values, as well as the thermostat and HVAC system setting at the beginning of the test, the drift phase. During this phase, a change in the indoor temperature may be detected from the initial value during the drift phase. The amount of time required for this phase may be a function of ambient air conditions, construction quality of the home and distribution system, and/or wind speed and solar absorption of the home, for example.

Example considerations during the drift phase are that 1) the space is held at a constant temperature prior to the start of the test so its contents are near equilibrium with the indoor ambient air; 2) external load factors are eliminated by making sure all windows and doors are closed and mechanical ventilation systems are turned off; and 3) the influence of both internal and solar gains are either minimized or accounted for.

Internal heat generation due to appliances, light usage and the like, which are commonly referred to as plug loads, can be accounted for by monitoring the electricity consumption of the building during the test, for example.

In some embodiments, the system may determine solar energy absorption, wherein thermodynamics of the building are further based on solar energy absorption. For example, solar absorption levels of the building may be a function of latitude, longitude, time of year and exposed surface area, among other things. The calculation methods to quantify the amount of solar energy absorbed by a building are well known to those skilled in the art, for example.

FIG. 5 depicts representative indoor and outdoor air temperature values, as well as the thermostat and HVAC system setting at the end of the Drift Phase of the test, which marks the beginning of the recovery phase. During the recovery phase of the present disclosure, the HVAC equipment is activated in either heating or cooling mode. The heating/cooling capacity of the equipment may be quantified in various ways, including through the use of published ratings corrected for actual operating conditions during the test, by measuring heating fuel or electricity usage via onsite meters, or by the inclusion of an equipment monitoring package that will measure equipment capacity directly, for example.

FIG. 6 illustrates an internet-connected, programmable thermostat for performing an automated test and calculation method for drift and recovery phases.

With known capacity, the HVAC system is monitored to determine the time needed to restore the building to original temperature conditions so that the total amount of thermal energy transfer during the drift phase can be quantified.

After accounting for internal heat generation and solar absorption, the building UA-value is calculated using the values for the measured amount of thermal energy transfer, the elapsed time during the drift period, and the average difference between indoor and outdoor air conditions.

Once the UA value of the building is defined, the peak heating and cooling loads can then be determined using the steady state conduction equation for a plane wall: q=UA·ΔT, where q is the peak heating/cooling load in Btu/hr, UA is the combined heat transfer resistance and surface area value in Btu/hr-° F., and ΔT=indoor−outdoor air temperature difference on design day in ° F. A sample dataset and calculation follows. FIGS. 1 and 2 illustrate representative indoor and outdoor air temperature values, thermostat settings, and furnace usage/runtime corresponding with the sample calculations. The following examples illustrate heating and cooling scenarios:

Heating Example Sample Location Based Weather Data:

-   -   Location: Brookings, SD     -   Design interior temp=70° F.     -   Design exterior temp=−9° F.

Drift Phase Data Measurements:

-   -   Start time: 10:00 PM     -   Interior start temp: 71° F.     -   Exterior start temp: 47° F.     -   End time: 7:00 am     -   Interior end temp: 67° F.     -   Exterior end temp: 33° F.

Recovery Phase Data Measurements:

-   -   Furnace capacity: 100,000 Btu/hr     -   Furnace recovery (time to restore space to original temp): 1.47         hr

Sample Calculations

-   -   Drift phase duration=9 hr     -   Average inside air temp=(71° F.+67° F.)/2=69° F.     -   Average outside air temp=(47° F.+33° F.)/2=40° F.     -   Total heat energy loss during drift phase=(100,000 Btu/hr*1.47         hr)=147,000 Btu     -   Rate of heat energy loss during drift phase=(147,000 Btu/9         hr)=16,333 Btu/hr     -   UA Value=[16,333 Btu/hr/(69° F.−40° F.)]=563.2 Btu/hr-° F.     -   Peak Heating Load, q=(563.2 Btu/hr-F)*(70° F.−(−9° F.))=44,493         Btu/hr

A starting and ending internal temperature values, starting and ending external temperature values, a duration of the first time period, an energy capacity of the temperature control system, and a duration of the second time period.

The calculation methodology above is just one example approach, and it is to be understood that other approaches may be used that may have improved accuracy, for example. Additionally, although the sample calculation performed above is based on the presence of cold outside air temperatures and use of the existing heating system, it could also be performed during the summer cooling season. In this case, the test would be performed by monitoring the temperature increase during the drift phase due to high outside air temperatures and the time to restore the space to its initial temperature with the cooling system during the recovery phase. As mentioned above, in the case of cooling, humidity may be used to perform the calculation as the following example illustrates.

Cooling Example Sample Location Based Weather Data:

-   -   Location: Brookings, SD     -   Elevation (above sea level): 1,621 ft     -   Design interior temp: 75° F./62.3° F. (wb/wb)     -   Design interior relative humidity: 50%         -   Humidity ratio: 0.0098 lbw/lba         -   **Humidity ratio may be a function of elevation, dry bulb             (db) temp and wet bulb (wb) temp     -   Design exterior temp: 86° F./71° F. (db/wb)     -   Design exterior relative humidity: 49%         -   Humidity ratio=0.0138 lb_(w)/lb_(a)     -   Design humidity ratio difference=(0.0138 lb_(w)/lb_(a)−0.0098         lb_(w)/lb_(a))=0.0040 lb_(w)/lb_(a)

Drift Phase Data Measurements:

Drift Phase Start

-   -   Start time: 12:00 AM     -   Interior start temp: 76° F./63.1° F. (db/wb)     -   Interior start relative humidity: 49.9%         -   Humidity ratio=0.0101 lb_(w)/lb_(a)     -   Exterior start temp: 83° F./72° F. (db/wb)     -   Exterior start relative humidity: 59.8%         -   Humidity ratio=0.0154 lb_(w)/lb_(a)

Drift Phase End

-   -   End time: 6:00 AM     -   Interior end temp: 80° F./67° F. (db/wb)     -   Interior end relative humidity: 51.9%         -   Humidity ratio=0.0120 lb_(w)/lb_(a)     -   Exterior end temp: 85° F./73° F. (db/wb)     -   Exterior end relative humidity: 57.5%     -   Humidity ratio=0.0158 lb_(w)/lb_(a)

Recovery Phase Data Measurements:

-   -   Air conditioner total cooling capacity: 27,500 Btu/hr     -   Air conditioner sensible cooling capacity: 22,000 Btu/hr     -   Air conditioner latent cooling capacity: 5,500 Btu/hr     -   Air conditioner recovery time: 1.65 hr

Sample Calculations

-   -   Drift phase duration=6 hr

Sensible Cooling Load

-   -   Average inside air temp=(76° F.+80° F.)/2=78° F.     -   Average outside air temp=(83° F.+85° F.)/2=84° F.     -   Sensible heat energy gain during drift phase=(22,000 Btu/hr*1.65         hr)=36,300 Btu     -   Rate of sensible heat energy gain during drift phase=(36,300         Btu/6 hr)=6,050 Btu/hr     -   UA Value=[6,050 Btu/hr/(84° F.−78° F.)]=1008.3 Btu/hr-° F.     -   Peak Sensible Cooling Load, qs=(1008.3 Btu/hr-F)*(86° F.−75°         F.)=11,092 Btu/hr

Latent Cooling Load

-   -   Average inside air humidity ratio=(0.0101 lb_(w)/lb_(a)+0.0120         lb_(w)/lb_(a))/2=0.0111 lb_(w)/lb_(a)     -   Average outside air humidity ratio=(0.0154 lb_(w)/lb_(a)+0.0158         lb_(w)/lb_(a))/2=0.0156 lb_(w)/lb_(a)     -   Average humidity ratio difference=(0.0156 lb_(w)/lb_(a)−0.0111         lb_(w)/lb_(a))=0.0045 lb_(w)/lb_(a)     -   Latent heat energy gain during drift phase=(5,500         Btu/hr*1.65=9,075 Btu     -   Rate of latent heat energy gain during drift phase=(9,075 Btu/6         hr)=1,513 Btu/hr     -   Peak Latent Cooling Load=1,513 Btu/hr*(0.0040         lb_(w)/lb_(a)/0.0045 lb_(w)/lb_(a))=1,345 Btu/hr

Total Cooling Load

-   -   Peak Total Cooling Load=11,092 Btu/hr+1,345 Btu/hr=12,437 Btu/hr

For cooling, the total cooling load may comprise a sensible and latent component, where heating loads only consist of the sensible component. Because the drift period in this example took place through the night, the UA value that was used to determine sensible cooling load could also be used to predict heating load for the home. Solar heat gain may be accounted for to determine the cooling load without impacting the UA value used to calculate heating load. Because of this, two tests may be performed in order to determine the heating and cooling loads for a home in some embodiments. One test may take place during the day and the other would take place through the night, for example.

FIG. 7 illustrates an example of special purpose computer systems 700 according to one embodiment. Computer system 700 includes a bus 702, network interface 704, a computer processor 706, a memory 708, a storage device 710, and a display 712.

Bus 702 may be a communication mechanism for communicating information. Computer processor 706 may execute computer programs stored in memory 708 or storage device 708. Any suitable programming language can be used to implement the routines of some embodiments including C, C++, Java, assembly language, etc. Different programming techniques can be employed such as procedural or object oriented. The routines can execute on a single computer system 700 or multiple computer systems 700. Further, multiple computer processors 706 may be used.

Memory 708 may store instructions, such as source code or binary code, for performing the techniques described above. Memory 708 may also be used for storing variables or other intermediate information during execution of instructions to be executed by processor 706. Examples of memory 708 include random access memory (RAM), read only memory (ROM), or both.

Storage device 710 may also store instructions, such as source code or binary code, for performing the techniques described above. Storage device 710 may additionally store data used and manipulated by computer processor 706. For example, storage device 710 may be a database that is accessed by computer system 700. Other examples of storage device 710 include random access memory (RAM), read only memory (ROM), a hard drive, a magnetic disk, an optical disk, a CD-ROM, a DVD, a flash memory, a USB memory card, or any other medium from which a computer can read.

Memory 708 or storage device 710 may be an example of a non-transitory computer-readable storage medium for use by or in connection with computer system 700. The non-transitory computer-readable storage medium contains instructions for controlling a computer system 700 to be configured to perform functions described above by some embodiments. The instructions, when executed by one or more computer processors 706, may be configured to perform that which is described in some embodiments.

Computer system 700 includes a display 712 for displaying information to a computer user. Display 712 may display a user interface used by a user to interact with computer system 700.

Computer system 700 also includes a network interface 704 to provide data communication connection over a network, such as a local area network (LAN) or wide area network (WAN). Wireless networks may also be used. In any such implementation, network interface 704 sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

Computer system 700 can send and receive information through network interface 704 across a network 714, which may be an Intranet or the Internet. Computer system 700 may interact with other computer systems 700 through network 714. In some examples, client-server communications occur through network 714. Also, implementations of some embodiments may be distributed across computer systems 700 through network 714.

Some embodiments may be implemented in a non-transitory computer-readable storage medium for use by or in connection with the instruction execution system, apparatus, system, or machine. The computer-readable storage medium contains instructions for controlling a computer system to perform a methods and techniques described by some embodiments. The computer system may include one or more computing devices. The instructions, when executed by one or more computer processors, may be configured to perform that which is described in some embodiments.

Further Examples

In one embodiment, the present disclosure includes a method for determining a building UA-value comprising: monitor indoor and outdoor air temperature during a drift phase over a first time period; monitor a temperature control system run time during a second time period when the temperature control system in the building restores indoor air conditions to an initial state at the beginning of the first time period; and determining the amount of heat energy change during the second time period.

In one embodiment, data for the internal and external air temperature, the temperature control system run time, and amount of heat energy change is used to determine a combined UA-value of the building and thermal energy distribution system.

In one embodiment, the combined UA-value is used to determine peak heating or cooling loads for the building.

In one embodiment, said monitoring steps use a data acquisition unit with an internet-connected thermostat.

In another embodiment, the present disclosure includes a method for determining thermodynamic behavior of a building comprising: during a first time period, measuring, from a first sensor located inside said building, a plurality of internal temperature values; and measuring, from one or more second sensors located outside of, but proximate to, said building, a plurality of external temperature values, wherein the plurality of internal temperature values correspond to a change in temperature inside the building from a first temperature to a second temperature during the first time period; activating a temperature control system to change the temperature inside the building from the second temperature to the first temperature; determining a duration of a second time period over which the temperature inside the building changes to meet the first temperature; and determining a thermodynamic property of the building is based on at least said measuring steps and said determining step.

In one embodiment, determining the thermodynamic property of the building is based at least on initial and final internal temperature values, initial and final external temperature values, a duration of the first time period, a known energy capacity of the temperature control system, and a duration of the second time period.

In one embodiment, determining further comprises calculating one or more average differences between the plurality of internal temperature values and the plurality of external temperature values.

In one embodiment, the method further comprising, prior to said first time period, maintaining a constant temperature inside the building to establish a temperature equilibrium between the temperature inside the building and the temperature outside the building.

In one embodiment, the temperature inside the building at the beginning of the first time period is approximately equal to the temperature inside the building at the end of the second time period.

In one embodiment, the first sensor is a thermostat.

In one embodiment, the thermodynamic property is a thermal resistance.

In one embodiment, the thermodynamic property is a peak heating load.

In one embodiment, the thermodynamic property is a peak cooling load.

In one embodiment, the plurality of internal temperature values are greater than the plurality of external temperature values, and wherein the temperature control system increases the temperature inside the building.

In one embodiment, the plurality of internal temperature values are less than the plurality of external temperature values, and wherein the temperature control system decreases the temperature inside the building.

In one embodiment, the temperature control system is a heating, ventilation, or air conditioning system.

In one embodiment, the one or more second sensors are from a weather station.

In one embodiment, the method further comprising, during the first time period, measuring one or more internal humidity values and one or more external humidity values.

In one embodiment, the method further comprising monitoring electricity consumption of the building during the first and second time periods, wherein determining the thermodynamic property of the building is further based on said electricity consumption.

In one embodiment, the method further comprising determining solar energy absorption of the building during the first and second time periods, wherein determining the thermodynamic property of the building is further based on said solar energy absorption.

In another embodiment, the present disclosure pertains to a system for determining thermodynamic behavior of a building comprising: one or more processors; one or more network interface units; a non-transitory computer readable medium having stored thereon one or more programs, which when executed by the one or more processors, causes the one or more processors to perform a method comprising: during a first time period, measuring, from a first sensor located inside said building, a plurality of internal temperature values; and measuring, from one or more second sensors located outside of, but proximate to, said building, a plurality of external temperature values, wherein the plurality of internal temperature values correspond to a change in temperature inside the building from a first temperature to a second temperature during the first time period; activating a temperature control system to change the temperature inside the building from the second temperature to the first temperature; determining a duration of a second time period over which the temperature inside the building changes to meet the first temperature; and determining a thermodynamic property of the building based on at least said measuring steps and said determining step.

In yet another embodiment, the present disclosure pertains to a non-transitory computer readable medium having stored thereon one or more programs, which when executed by the one or more processors, causes the one or more processors to perform a method comprising: during a first time period, measuring, from a first sensor located inside said building, a plurality of internal temperature values; and measuring, from one or more second sensors located outside of, but proximate to, said building, a plurality of external temperature values, wherein the plurality of internal temperature values correspond to a change in temperature inside the building from a first temperature to a second temperature during the first time period; activating a temperature control system to change the temperature inside the building from the second temperature to the first temperature; determining a duration of a second time period over which the temperature inside the building changes to meet the first temperature; and determining a thermodynamic property of the building based on at least said measuring steps and said determining step.

The above description illustrates various embodiments of the present disclosure along with examples of how aspects of the particular embodiments may be implemented. The above examples should not be deemed to be the only embodiments, and are presented to illustrate the flexibility and advantages of the particular embodiments as defined by the following claims. Based on the above disclosure and the following claims, other arrangements, embodiments, implementations and equivalents may be employed without departing from the scope of the present disclosure as defined by the claims. 

What is claimed is:
 1. A method for determining a building UA-value comprising: monitor indoor and outdoor air temperature during a drift phase over a first time period; monitor a temperature control system run time during a second time period when the temperature control system in the building restores indoor air conditions to an initial state at the beginning of the first time period; and determining the amount of heat energy change during the second time period.
 2. The method in claim 1 wherein data for the internal and external air temperature, the temperature control system run time, and amount of heat energy change is used to determine a combined UA-value of the building and thermal energy distribution system.
 3. The method of claim 6 wherein the combined UA-value is used to determine peak heating or cooling loads for the building.
 4. The method of claim 1 wherein said monitoring steps use a data acquisition unit with an internet-connected thermostat.
 5. A method for determining thermodynamic behavior of a building comprising: during a first time period, measuring, from a first sensor located inside said building, a plurality of internal temperature values; and measuring, from one or more second sensors located outside of, but proximate to, said building, a plurality of external temperature values, wherein the plurality of internal temperature values correspond to a change in temperature inside the building from a first temperature to a second temperature during the first time period; activating a temperature control system to change the temperature inside the building from the second temperature to the first temperature; determining a duration of a second time period over which the temperature inside the building changes to meet the first temperature; and determining a thermodynamic property of the building is based on at least said measuring steps and said determining step.
 6. The method in claim 5 wherein determining the thermodynamic property of the building is based at least on initial and final internal temperature values, initial and final external temperature values, a duration of the first time period, a known energy capacity of the temperature control system, and a duration of the second time period.
 7. The method of claim 5 wherein determining further comprises calculating one or more average differences between the plurality of internal temperature values and the plurality of external temperature values.
 8. The method of claim 5 further comprising, prior to said first time period, maintaining a constant temperature inside the building to establish a temperature equilibrium between the temperature inside the building and the temperature outside the building.
 9. The method of claim 5 wherein the temperature inside the building at the beginning of the first time period is approximately equal to the temperature inside the building at the end of the second time period.
 10. The method of claim 5 wherein the first sensor is a thermostat.
 11. The method of claim 5 wherein the thermodynamic property is a thermal resistance.
 12. The method of claim 5 wherein the thermodynamic property is a peak heating load.
 13. The method of claim 5 wherein the thermodynamic property is a peak cooling load.
 14. The method of claim 5 wherein the plurality of internal temperature values are greater than the plurality of external temperature values, and wherein the temperature control system increases the temperature inside the building.
 15. The method of claim 5 wherein the plurality of internal temperature values are less than the plurality of external temperature values, and wherein the temperature control system decreases the temperature inside the building.
 16. The method of claim 5 wherein the temperature control system is a heating, ventilation, or air conditioning system.
 17. The method of claim 5 wherein the one or more second sensors are from a weather station.
 18. The method of claim 5 further comprising, during the first time period, measuring one or more internal humidity values and one or more external humidity values.
 19. The method of claim 5 further comprising monitoring electricity consumption of the building during the first and second time periods, wherein determining the thermodynamic property of the building is further based on said electricity consumption.
 20. The method of claim 5 further comprising determining solar energy absorption of the building during the first and second time periods, wherein determining the thermodynamic property of the building is further based on said solar energy absorption.
 21. A system for determining thermodynamic behavior of a building comprising: one or more processors; one or more network interface units; a non-transitory computer readable medium having stored thereon one or more programs, which when executed by the one or more processors, causes the one or more processors to perform a method comprising: during a first time period, measuring, from a first sensor located inside said building, a plurality of internal temperature values; and measuring, from one or more second sensors located outside of, but proximate to, said building, a plurality of external temperature values, wherein the plurality of internal temperature values correspond to a change in temperature inside the building from a first temperature to a second temperature during the first time period; activating a temperature control system to change the temperature inside the building from the second temperature to the first temperature; determining a duration of a second time period over which the temperature inside the building changes to meet the first temperature; and determining a thermodynamic property of the building based on at least said measuring steps and said determining step.
 22. A non-transitory computer readable medium having stored thereon one or more programs, which when executed by the one or more processors, causes the one or more processors to perform a method comprising: during a first time period, measuring, from a first sensor located inside said building, a plurality of internal temperature values; and measuring, from one or more second sensors located outside of, but proximate to, said building, a plurality of external temperature values, wherein the plurality of internal temperature values correspond to a change in temperature inside the building from a first temperature to a second temperature during the first time period; activating a temperature control system to change the temperature inside the building from the second temperature to the first temperature; determining a duration of a second time period over which the temperature inside the building changes to meet the first temperature; and determining a thermodynamic property of the building based on at least said measuring steps and said determining step. 